High-dose intravenous gammaglobulin for idiopathic thrombocytopenic purpura in childhood

Seven children with chronic or intermittent and six with acute idiopathic thrombocytopenic purpura (ITP) were treated with large intravenous doses of polyvalent, intact immunoglobulin (Ig). In all patients the platelet count rose sharply within 5 days, but the initial response and the subsequent course varied from patient to patient. Among children with chronic ITP the initial response was more marked in splenectomised than in non-splenectomised patients. Among those with acute ITP the two who remained Ig dependent had a smaller initial response than the four patients who required no maintenance treatment. During the 90-110 days of observation five of six patients with chronic ITP could be maintained with Ig alone. No untoward effects of Ig therapy were observed.

Transient reversal of thrombocytopenia in idiopathic thrombocytopenic purpura by high-dose intravenous gamma globulin

Since recent observations indicate that treatment with high-dose intravenous polyvalent intact immunoglobulin leads to a rapid reversal of thrombocytopenia in the idiopathic thrombocytopenic purpura (ITP) of childhood, we decided to apply this treatment to adults with ITP and to test the possibility that the effect of the immunoglobulin might be attributable to transient blockade of the reticuloendothelial system. Using sequential clearance studies of autologous 99mTc-labeled and anti-Rh(D)-sensitized erythrocytes in four adults with ITP who were treated with total doses of 1 to 1.5 g of immunoglobulin per kilogram of body weight, we found that a transient rise in platelet counts to normal levels within four to five days was accompanied by a marked temporary prolongation of the immune-particle clearance time. These data suggest that commercial intravenous immunoglobulin preparations may interfere with phagocyte Fc-receptor-mediated immune clearance. Since platelets in ITP treated with immunoglobulin were fully hemostatic, this type of therapy may allow surgical procedures to be performed safely in patients with this disease.

Effect of intravenous immunoglobulin in immune thrombocytopenia

The rapid rise in platelet count after immunoglobulin treatment in acute and chronic forms of idiopathic thrombocytopenic purpura (ITP), autoimmune neutropenia, and post-transfusion purpura is well documented. It is suggested that the rise in platelet count is due to competitive inhibition of the macrophage binding of platelets by preferential sequestration of immunoglobulin-coated red blood cells. Measurement of haptoglobin levels, a sensitive indicator of haemolysis, suggests that clinically inapparent haemolysis occurs during immunoglobulin therapy of ITP patients. In-vitro experiments confirm that there is immunoglobulin coating of red blood cells. The hypothesis is further supported by the findings that immunoglobulin treatment in autoimmune haemolytic anaemia is ineffective, and that platelet counts rise in some ITP patients after induction of a mild haemolytic syndrome by injection of anti-Rho (D).

Thrombotic Microangiopathy and the Kidney

Thrombotic microangiopathy can manifest in a diverse range of diseases and is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ injury, including AKI. It can be associated with significant morbidity and mortality, but a systematic approach to investigation and prompt initiation of supportive management and, in some cases, effective specific treatment can result in good outcomes. This review considers the classification, pathology, epidemiology, characteristics, and pathogenesis of the thrombotic microangiopathies, and outlines a pragmatic approach to diagnosis and management.

Intravenous immunoglobulin versus oral corticosteroids in acute immune thrombocytopenic purpura in childhood

In a randomised, multicentre study intravenous IgG was compared with oral corticosteroids in 108 children with untreated acute immune thrombocytopenic purpura. IgG was an efficient treatment with no severe untoward reactions. The effects of corticosteroids and IgG were identical for rapid responders, who accounted for 62% of all patients. In contrast, patients requiring more than initial treatment responded better if randomised to IgG. The serum IgG level increased two-fold after IgG. A significant rise in IgM levels was observed after both IgG and corticosteroids. The platelet-associated IgG index was high in 75% of all patients. No significant differences between the two treatment groups were found, but rapid responders had a smaller mean initial platelet-associated IgG index which returned more rapidly and more permanently to normal than that of slow responders.

Mechanisms of response to treatment in autoimmune thrombocytopenic purpura

To determine the mechanisms of an increase in the platelet count after therapy for autoimmune thrombocytopenic purpura, we determined the survival time and localization of radiolabeled autologous platelets and measured platelet-associated immunoglobulin levels before and after prednisone therapy or splenectomy in 19 patients with the disease. Eleven of 12 patients (92 percent) responded to prednisone with a mean threefold increase in the platelet count, resulting from increased platelet production (P less than 0.005); platelet survival was unchanged. Treatment with steroids failed in only one patient, whose pretreatment platelet production was already above normal. After splenectomy, 6 of 10 patients had a mean fourfold rise in the platelet count that correlated with increased platelet survival (P less than 0.005), together with improved platelet recovery (the percentage of platelets circulating in the blood immediately after the injection). Platelet production was unchanged. Base-line 111In-labeled platelet localization in the liver was normal in five patients in whom splenectomy was effective and increased to above normal in two of three in whom it was ineffective. Total platelet localization in the liver and spleen decreased by more than half after successful splenectomy (P less than 0.001), whereas it decreased by less than 25 percent after unsuccessful splenectomy. Platelet-associated immunoglobulin levels neither predicted nor correlated with treatment responses to prednisone or splenectomy. We conclude that prednisone improves platelet counts primarily by increasing platelet production, whereas the effect of splenectomy is to prolong platelet survival. Baseline measurements of platelet turnover and of platelet localization in the liver may be helpful in predicting the response to prednisone or splenectomy, respectively.

Thrombocytopenia in homosexual patients. Prognosis, response to therapy, and prevalence of antibody to the retrovirus associated with the acquired immunodeficiency syndrome

Thirty-three homosexual patients with thrombocytopenia (mean [+/- SE] platelet count, 50 000 +/- 7000/mm3; range, 7 to 135 000/mm3) have been followed for a mean period of 20 +/- 2 months. Six patients have developed the acquired immunodeficiency syndrome 1 to 37 months after the diagnosis of thrombocytopenia. Six patients spontaneously reverted to normal platelet counts 5 to 27 months (median, 10 months) after the diagnosis of thrombocytopenia, in the absence of splenectomy and while not receiving corticosteroids. Sixteen of seventeen patients had a moderate to excellent response while on corticosteroid treatment. Ten of ten patients had an excellent response to splenectomy which has persisted. Fifteen patients did not require treatment for their thrombocytopenia. Thirteen of fourteen patients had antibody against the retrovirus associated with the acquired immunodeficiency syndrome, as did 4 of 12 homosexual controls without thrombocytopenia. Thrombocytopenia in homosexuals is part of the complex related to the acquired immunodeficiency syndrome.

Treatment of autoimmune thrombocytopenic purpura with rhesus antibodies (anti-Rh0(D)

There is evidence that blockade of the reticuloendothelial system (RES) by sequestration of autologous red blood cells (RBC) leads to an elevation of platelet counts in immune thrombocytopenia. To substantiate this hypothesis, 10 Rh0(D)-positive adult patients (9 female, 1 male) with chronic autoimmune thrombocytopenic purpura (ITP) (1 to 21 years duration) were treated with low doses of intravenous IgG-anti-Rh0(D) (200 to 1,000 micrograms per dose; 300 to 3,600 micrograms per course; administration within 1 to 5 days). All patients improved clinically as indicated by cessation of bleeding. In eight out of ten patients there was a rise in platelet count. Platelet increments were excellent (greater than 100 X 10(9)/l) in one, good (50-100 X 10(9)/l) in three, fair (20-50 X 10(9)/1) in two and low (10-20 X 10(9)/1) in two patients. Splenectomized patients (N = 4) had a poorer response than non-splenectomized patients (N = 6) with mean increments of 16 X 10(9)/l (range 5-43 X 10(9)/l) versus 60 X 10(9)/l (range 10-110 X 10(9)/l). The increase in platelet counts persisted for seven to over 150 days. Transient and slight signs of haemolysis developed in seven out of ten patients (haemoglobin remained stable; increase of lactate dehydrogenase (greater than 250 IU/l) in four, decrease of haptoglobin (less than 60 mg/dl) in five patients). The direct antiglobulin test became positive in all cases due to IgG1 without complement fixation. We conclude that the interaction of antibody-coated RBC with macrophages (and, probably, other means of RBC alteration) is a feasible therapeutic approach in selected cases of ITP and related conditions.

Fetal platelet counts in the obstetric management of immunologic thrombocytopenic purpura

The optimal method of infant delivery for gravida women with immunologic thrombocytopenic purpura (ITP) is controversial because of the unpredictability of the fetus developing thrombocytopenia and the uncertainty of the relation between vaginal birth and intracranial hemorrhage in thrombocytopenic infants. We have employed the technique of platelet counts on fetal scalp blood obtained prior to or early in the course of labor in 12 patients with ITP. A count of 50,000/cu mm, selected on the basis of literature review and retrospective analysis of our own experience, was used to define fetal thrombocytopenia. Three thrombocytopenic fetuses were delivered by cesarean section. Trial labor was permitted in the other nine cases in which fetal scalp platelet count exceeded 50,000/cu mm. The outcome was good in all instances. If cesarean section is to be employed in ITP patients to obviate the potential danger of fetal hemorrhage with vaginal delivery, the use of platelet counts of fetal scalp blood seems to provide the most rational basis for management at present.

United States Thrombotic Thrombocytopenic Purpura Apheresis Study Group (US TTP ASG): multicenter survey and retrospective analysis of current efficacy of therapeutic plasma exchange

Thrombotic thrombocytopenic purpura (TTP) remains enigmatic from the perspective of its etiology, pathophysiology, and treatment. Once recognized, the accepted standard of care for TTP is daily therapeutic plasma exchange (TPE). However, the diversity in TPE treatment protocols has made comparisons of clinical research between institutions difficult. This study strived to assess the current practice of TPE in order to provide direction for prospective controlled clinical trials. Twenty large apheresis centers within the United States comprising the US TTP ASG responded to a survey to establish the current status of TPE in TTP. A retrospective analysis from data provided by 14 of 20 centers included 115 initial presentations of primary TTP with an overall mortality rate of 10% and relapse rate of 37%. The majority of deaths (58%) occurred within 48 hours of presentation. Variation in therapeutic targets (platelet count [plt] and serum LDH) and the number of plasma volumes exchanged per procedure did not affect the relapse rate. Initial plt and LDH were not predictive of mortality. Response, relapse, and mortality rates with the combination of 5% albumin for the initial 50% of TPE followed by plasma for the final 50% of TPE as replacement were comparable or possibly better than plasma-only replacement strategies. Forty percent of centers routinely used a TPE taper; however, there was no statistical difference in relapse rates comparing the taper and non-taper sub-groups. By controlling for adjunctive modalities such as steroids and anti-platelet agents, it is hoped that future prospective clinical trials may optimize the role of TPE in TTP, minimize patient exposure to blood products and procedures, shorten the clinical course of TTP, and reduce mortality.

Serum immunoglobulin and transferrin levels after childhood splenectomy

IgG, IgA, IgM, and transferrin levels were measured in sera from a group of children who had been subjected to splenectomy in the previous 10 years. In those children splenectomized for hereditary spherocytosis, idiopathic thrombocytopenic purpura, or traumatic rupture, mean IgM levels were significantly lower and mean transferrin levels were significantly higher than in sera from control children. Children splenectomized for thalassaemia major had a significantly raised mean IgG level, while children splenectomized for portal hypertension had a raised mean IgA level. However, IgG and IgA levels in patients who had suffered splenic rupture did not differ from control values. The finding of high transferrin levels after splenectomy supports the concept of an immunological function for this protein in addition to its iron-binding capacity.

Splenectomy for primary and recurrent immune thrombocytopenic purpura (ITP). Current criteria for patient selection and results

Of 565 patients with thrombocytopenia admitted to Duke University Hospital between 1975 and 1985, 100 had splenectomy. Ninety-eight patients had failed chronic immunosuppressive therapy and three patients had acute intracranial bleeding or total absence of platelets in the peripheral blood smear, and had urgent splenectomy. At primary splenectomy, accessory spleens were identified and resected in 18% of patients. There was no operative mortality. Fifty-eight patients had an excellent response to splenectomy and their steroids were tapered off within 3 weeks. Thirteen patients had a poor response to primary splenectomy of whom eight remitted spontaneously and five required accessory splenectomy resulting in complete remission in three patients. Twenty-nine patients were considered nonresponders, 25 of whom had radionuclide scanning for accessory spleens. Seven of these patients had accessory spleens identified but only four consented to accessory splenectomy. In three of the four patients, a complete remission was achieved. Neither platelet antibody titers nor measurements of platelet survival or turnover predicted platelet response to splenectomy. However, immune thrombocytopenic purpura (ITP) in older patients was significantly less likely to respond to splenectomy. These data support continuing use of splenectomy in selected patients with ITP and an aggressive search for accessory spleens in patients who relapse since they are easily localized at operation by hand-held isotope detector probe.

The use and mechanism of action of intravenous immunoglobulin in the treatment of immune haematologic disease

In summary, intravenous gammaglobulin appears to be a very useful treatment of immune haematologic disease. Almost all patients with ITP treated with IVIg will have an increase in their platelet counts lasting at least 2 weeks. Some of these patients will derive long-term benefit from the IVIg and many can maintain their platelet counts by periodic single outpatient infusions. Patients with immune neutropenia are also likely to benefit by IVIg treatment which may be of particular benefit due to its not interfering with phagocyte function. RES blockade is a well-documented mechanism of action immediately after IVIg infusion and platelet antibody synthesis may decrease in some patients; IVIg does not appear to protect platelets from platelet antibodies.

(NZW x BXSB)F1 mouse. A new animal model of idiopathic thrombocytopenic purpura

A decrease in thrombocyte count was observed in (NZW x BXSB)F1 (W/B F1) mice at the age of greater than 5 mo, whereas megakaryocyte counts were found to increase in such mice. FACS analyses revealed the presence of both platelet-associated antibodies (PAA) and circulating antiplatelet antibodies. There is a correlation between the presence of these antibodies and the degree of thrombocytopenia. The transplantation of normal bone marrow cells from BALB/c nu/nu mice to W/B F1 mice was found to have preventative and curative effects on thrombocytopenia; the mice showed normal platelet counts and no evidence of circulating antiplatelet antibodies. These results indicate that thrombocytopenia in W/B F1 mice is due to the presence of antibodies to platelets. We therefore think that W/B F1 mice serve as a useful animal model of idiopathic thrombocytopenic purpura (ITP) not only for elucidating the mechanism of the development of antiplatelet antibodies, but also for characterizing autoantibodies to platelets.

Acute renal failure resulting from intravenous immunoglobulin therapy

In idiopathic thrombocytopenic purpura, a known immune-mediated disorder, intravenous IgG is the treatment of choice. Success and the lack of side effects of intravenous IgG in the treatment of idiopathic thrombocytopenic purpura have encouraged consideration of its use in the treatment of neurologic disorders of presumed autoimmune pathogenesis. In this report, we describe two patients who developed acute renal failure following intravenous IgG treatment. The first patient had chronic inflammatory demyelinating polyneuropathy and was treated with intravenous IgG instead of prednisone because of preexisting diabetes. The second patient had idiopathic thrombocytopenic purpura and received intravenous IgG treatment as part of standard care. The patient with idiopathic thrombocytopenic purpura had unrelated bilateral high-grade renal artery stenosis. Both patients had a creatinine level of 140 mumol/L (1.6 mg/dL) prior to treatment. Renal biopsies performed during acute renal failure in each patient demonstrated marked swelling and vacuolization of the proximal tubular epithelial cytoplasm typical of high-solute-load-induced damage (similar to that associated with the use of mannitol). This report draws attention to the importance of screening for impaired renal function before intravenous IgG therapy is initiated. The patients we describe received standard doses of intravenous IgG at the recommended infusion rate yet developed oliguric renal failure. Awareness of serious side effects and recognition of predisposing factors provide means of avoiding known life-threatening complications of intravenous IgG therapy.

A dose of 75 microg/kg/d of i.v. anti-D increases the platelet count more rapidly and for a longer period of time than 50 microg/kg/d in adults with immune thrombocytopenic purpura

Treatment with 75 microg/kg/d intravenous (i.v.) anti-D was compared with 50 microg/kg/d in a prospective randomized study of 27 RhD-positive, human immunodeficiency virus-negative, adult, acute, non-splenectomized patients with immune thrombocytopenic purpura (ITP) and platelet counts < or = 30 x 109/l. The higher dose resulted in greater median d 1 (43 x 109/l vs. 7.5 x 109/l; P = 0.012) and d 7 (153 x 109/l vs. 64.5 x 109/l; P = 0.001) platelet increases despite no greater haemoglobin decrease. Children with acute ITP receiving 75 microg/kg/d had overnight platelet increases in seven out of nine cases. The duration of effect at the 75 microg/kg/d dose was 46 d vs. 21 d (P = 0.03). Adverse events were mild to moderate and ameliorated with prednisone and acetaminophen premedication.